What was found
(CAN) DURING CLIMB, FLIGHT CREW NOTICED OIL PRESSURE FLUCTUATION FOLLOWED BY AN IMMEDIATE ILLUMINATION OF NR 1 ENGINE LOW OIL PRESSURE LIGHT. FLIGHT CREW IMMEDIATELY SHUTDOWN THE ENGINE IN FLIGHT. ACFT RETURNED TO ITS AIRPORT OF ORIGIN WITH 1 ENGINE OPERATIONAL. AN UNEVENTFUL LANDING WAS PERFORMED. UPON INSPECTION OF THE LT ENGINE, AN OIL LEAK WAS OBSERVED FROM THE ENGINE PRESSURE REGULATING VALVE AND THE ATTACHING BOLT WAS SEEN TO BE NOT SEATING FLUSHED FROM THE COVER AND THE HELICOIL INSERT WAS FOUND DAMAGED. THE HELICOIL WAS REPLACED.